When a vehicle having a stabilizer apparatus runs at a curve, inputs are provided to a left suspension mechanism and a right suspension mechanism so as to have phases opposite to each other in an upper direction and in a lower direction, a left arm portion and a right arm portion bend in directions opposite to each other, and a torsion portion is twisted in a stabilizer of the stabilizer apparatus. In this manner, the stabilizer of the stabilizer apparatus functions as a spring inhibiting the vehicle roll. The stabilizer apparatus has been fixed to a vehicle body of vehicle by fastening a bracket with a bolt via a bush which is made of rubber and is provided in the stabilizer.
However, a load is generated by centrifugal force when a vehicle runs at a curve, and the position of the bush to the torsion portion is moved by the load against frictional force therebetween. Even when opposite centrifugal force is generated or the vehicle runs straight, the bush does not return the initial position, and the movement of the bush is maintained. Due to this, for example, anti-roll effect by the stabilizer cannot be obtained, excessive load is provided to stabilizer links which are connected to both ends of the stabilizer, and interference risk of the stabilizer with surrounding parts thereof may be high.
In order to prevent the movement of the bush, an aluminum ring or an iron ring is caulked so as to be used as a movement stopper member. Two of the movement stopper members are used for one stabilizer so as to be respectively disposed at a left side and a right side of the stabilizer. On the other hand, in order to prevent the movement of the bush, the bush made of rubber may be directly fixed at the torsion portion by using an adhesive or by performing heat curing.
In a production method for a hollow stabilizer apparatus using an aluminum ring as a movement stopper member, first, for example, an electroseamed pipe, which has a predetermined length by cutting, is subjected to cold working, so that the electroseamed pipe is formed into a stabilizer shape. Next, heating such as hardening and tempering is performed on the half-finished stabilizer. Next, shot peening, in which shots are projected onto the half-finished stabilizer, is performed on the half-finished stabilizer. Next, the half-finished stabilizer is subjected to coating. Next, an aluminum ring, which is half-divided or composed of two pieces, is caulked so as to be used as a movement stopper member.
In a production method for a hollow stabilizer apparatus using an iron ring as a movement stopper member, first, for example, an electroseamed pipe, which has a predetermined length by cutting, is subjected to bending working, so that an arm portion is formed. Next, the electroseamed pipe having the arm portion passes through an iron ring having a C-shape. An end portion of the arm portion is subjected to working. For example, a flattened portion or a mounting hole, at which the stabilizer link is mounted, is formed at the end portion of the arm portion by forging or the like. The iron ring is caulked, and coating is performed.
In a fixing method of a bush made of rubber, the bush is integrally molded by injection molding to a torsion portion of a stabilizer, and the bush is subjected to heat curing so as to be cured. This technique is disclosed in Japanese Unexamined Patent Application Publication Nos. 2001-163026 and 2001-165127.
However, in the method using the aluminum ring, the aluminum ring, which is half-divided or composed of two pieces, is caulked so as to be fixed to the torsion portion. This aluminum ring has a connection portion which is a weak structure, so that the strength of the aluminum ring is low. Due to this, when the aluminum ring receives a load, the caulked condition of the aluminum ring is easily broken. Thus, the fix strength of the aluminum ring is easily deteriorated, and the fix positions of the stabilizer at the left side and the right side of the vehicle are unbalanced, and the effects by the stabilizer cannot be obtained sufficiently during running of the vehicle at a curve. As a result, the reliability of the stabilizer apparatus is not sufficient.
The peripheral surface of the torsion portion on which the aluminum ring, the iron ring, or the bush is mounted is almost smooth. Due to this, in the case that the aluminum ring or the iron ring is caulked so as to be provided on the torsion portion or the bush made of rubber is cured so as to be provided thereon, when the bush receives a load by centrifugal force, the bush easily moves. Thus, the fix positions of the stabilizer at the left side and the right side of the vehicle are unbalanced, and the effects by the stabilizer cannot be obtained sufficiently during running of the vehicle at a curve. As a result, the reliability of the stabilizer apparatus is not sufficient.
When the aluminum ring and the iron ring are used for the movement stopper member, they are heavier than the resin movement stopper. Due to this, the weight of the stabilizer apparatus cannot be reduced. The aluminum ring is higher than the iron ring in deformation resistance, and the aluminum ring is thereby formed in a circular shape so as to be easily caulked. Due to this, it is necessary that the torsion portion pass through the aluminum ring before a flattened portion or a mounting hole, at which the stabilizer link is mounted, is formed at the end portion of the arm portion by forging or the like. That is, it is necessary that the electroseamed pipe passes through the iron ring after bending forming of the electroseamed pipe and before coating of the half-finished stabilizer. Due to this, it is necessary to perform working for forming of a flattened portion or a mounting hole without falling and separating of the iron ring which is not caulked, so that handling is troublesome.